Tens of thousands of Latvians marched through gray, wet streets Saturday behind the body of a man who officials of the independence-minded republic say was killed by Soviet soldiers.

Before the 2 1/2-mile-long procession for Roberts Murnieks, 39, began its slow passage over the damp cobblestones of the Latvian capital, a three-hour funeral service was held in St. Albert's Roman Catholic church.Weeping women lined the sidewalks to place flowers beside the embalmed body, which was carried atop the coffin.

"He is our martyr, a martyr for Latvian independence," said Ina Borisenora, a student. "Any one of us could have been in his place."

Murnieks, a chauffeur for the Latvian transport minister, was shot Wednesday while driving a government car. The Latvian government said he was killed during a rampage by "black beret" troops controlled by the Soviet Interior Ministry.

Three days before the shooting in Latvia, Soviet soldiers stormed the radio-television center in neighboring Lithuania. Fourteen people were killed and 230 injured.

The deaths were the first since the standoff in the Baltics began early last year. Lithuania declared independence on March 11, and Latvia followed suit May 4. Estonia, the third Baltic republic, has pledged to restore full independence gradually.

Alexander Bessmertnykh, the new Soviet foreign minister, "expressed concern" to U.S. Ambassador Jack Matlock that U.S. media and Congress were portraying the conflict in a way that could aggravate the situation, Foreign Ministry spokesman Vitaly Churkin said.

On the day Murnieks was killed, the Soviet soldiers shot up a truck, set fire to cars and stopped vehicles randomly at main entrances to Riga. They frisked and terrorized people, and fired on an ambulance carrying a sick woman and two children.

When Murnieks drove by in a gray Volga, Latvian officials say, the black berets opened fire with automatic rifles. They say a bullet hit Murnieks, the lone occupant of the car, in the head and he died in a hospital soon afterward.

At the funeral, thousands of people filed past the body, which still had bloodstains under the fingernails and in the nostrils.

Latvian men sat by log fires not far away, guarding government buildings.

In front of the parliament, a huge crane deposited concrete blocks that were cemented together in a protective barrier against military attack. The blocks replaced heavy construction machinery that had served as barricades earlier in the week.

Citizens of Riga and people from the countryside have guarded buildings in the city for nearly a week. In Lithuania also, fortifications have been erected around that republic's parliament building in case of an assault by Soviet troops.